Novel Fluorescent and Colored Proteins, and Polynucleotides that Encode These Proteins

ABSTRACT

The subject invention provides new fluorescent and/or colored proteins, and polynucleotide sequences that encode these proteins. The subject invention further provides materials and methods useful for expressing these detectable proteins in biological systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending applicationU.S. Ser. No. 12/240,241, filed Sep. 29, 2008; which is a continuationof co-pending application U.S. Ser. No. 11/657,235, filed Jan. 23, 2007,now abandoned; which is a continuation application of U.S. Ser. No.11/058,952, filed Feb. 16, 2005, now U.S. Pat. No. 7,230,080, which arehereby incorporated by reference in their entirety.

GOVERNMENT SUPPORT

The subject matter of this application has been supported in part byU.S. Government Support under NIH RO1 GM066243-01. Accordingly, the U.S.Government has certain rights in this invention.

FIELD OF THE INVENTION

The present invention relates to novel fluorescent and colored proteins,and their use. These materials and methods are particularly advantageousfor labeling and detection technology. Specifically, exemplified arenovel colored and/or fluorescent proteins, and mutants thereof, isolatedfrom marine organisms. These new proteins offer a wider array of colorsand biochemical features compared to existing wild-type greenfluorescent protein (GFP) or its modified variants utilized in currentlabeling and detection technology.

BACKGROUND OF THE INVENTION

Genetic markers are important for monitoring gene expression andtracking movement of proteins in cells. Markers have been extensivelyused for monitoring biological activity of genetic elements such aspromoters, enhancers and terminators, and other aspects of generegulation in numerous biological systems. Over the years numerousmarker genes have been developed and utilized widely in molecular andgenetic studies aimed at the identification, isolation andcharacterization of genetic regulatory elements and genes, and thedevelopment of gene transfer techniques. In general, markers can begrouped into selectable markers and reporter markers.

Selectable markers are typically enzymes with catalytic capability toconvert chemical substrates usually harmful to host cells into non-toxicproducts, thus providing transformed host cells a conditionallyselectable growth advantage under selective environment and allowing therecovery of stable transformants after transformation. A number ofcommonly used selectable markers include those that confer resistancecharacteristics to antibiotics (Gritz and Davies 1983; Bevan et al.,1983) and herbicides (De Block et al., 1987), and those with enzymaticactivity to detoxify metabolic compounds that can adversely affect cellgrowth (Joersbo and Okkels 1996).

Reporter markers are compounds that provide biochemically assayable oridentifiable activities. Reporter markers have been widely used instudies to reveal biological functions and modes of action of geneticelements such as promoters, enhancers, terminators, and regulatoryproteins including signal peptides, transcription factors and relatedgene products. Over the years, several reporter markers have beendeveloped for use in both prokaryotic and eukaryotic systems, includingβ-galactosidase (LacZ) (Stanley and Luzio 1984), β-glucuronidase (GUS)(Jefferson et al., 1987; U.S. Pat. No. 5,268,463), chloramphenicolacetyltransferase (CAT) (Gorman et al., 1982), green fluorescent protein(GFP) (Prasher et al., 1992; U.S. Pat. No. 5,491,084) and luciferase(Luc) (Ow et al., 1986).

Among reporter markers, GUS offers a sensitive and versatile reportingcapability for gene expression in plants. β-glucuronidase or GUS,encoded by the uidA gene from Escherichia coli, catalyzes the conversionof several colorigenic and fluorogenic glucorogenic substrates such asp-nitrophenyl β-D-glucuronide and 4-methylumbelliferyl β-D-glucuronideinto easily detectable products. GUS activity can be measured by highlysensitive colorimetric and fluorimetric methods (Jefferson et al.,1987). However, the GUS assay often requires total destruction of thesample tissues or exposure of sample tissues to phytotoxic chemicalsubstrates. This prevents repeated use of the same sample tissue forcontinuous expression analysis and precludes the recovery oftransformants from analyzed materials.

Recently, GFP isolated from the Pacific Northwest jellyfish (Aequoreavictoria) has become an important reporter marker for non-destructiveanalysis of gene expression. GFP fluoresces in vivo by receiving lightenergy without the involvement of any chemical substrates. Thus, GFP isespecially suitable for real time and continuous monitoring of temporaland spatial control of gene expression and protein activities withoutany physical damage to assay samples.

The gene for GFP has been cloned and used as a reporter gene, which canbe expressed as a functional transgene in living organisms, marking theorganisms with fluorescent color and thus allowing detection of thoseorganisms. Accordingly, GFP has become a versatile fluorescent markerfor monitoring a variety of physiological processes, visualizing proteinlocalization and detecting the expression of transferred genes invarious living systems, including bacteria, fungi, and mammaliantissues.

This in vivo labeling and detection technology was originally based on asingle fluorescent protein: the green fluorescent protein from Aequoreavictoria. Numerous modifications have been made to alter the spectralproperties of GFP to provide for significant enhancement in fluorescenceintensity (Prasher et al., 1992; Cubitt et al., 1995, Heim et al., 1994,1995; Cormack et al., 1996; U.S. Pat. No. 5,804,387). In addition, GFPgenes have been modified to contain more silent base mutations thatcorrespond to codon-usage preferences in order to improve its expressionefficacy, making it a reporter gene in both animal and plant systems(U.S. Pat. Nos. 5,874,304; 5,968,750; and 6,020,192).

In addition to GFP, there are now a number of other fluorescentproteins, substantially different from GFP, which are being developedinto biotechnology tools. Most prominent of these proteins is the redfluorescent protein DsRed. See, for example, Labas, Y. A., N. G.Gurskaya, Y. G. Yanushevich, A. F. Fradkov, K. A. Lukyanov, S. A.Lukyanov and M. V. Matz. (2002) “Diversity and evolution of the greenfluorescent protein family” Proc Natl Acad Sci USA 99:4256-4261 andMatz. M. V., K. A. Lukyanov and S. A. Lukyanov (2002) “Family of thegreen fluorescent protein: journey to the end of the rainbow” Bioessays24: 953-959.

Labeling technologies based on GFP and related proteins have becomeindispensable in such areas as basic biomedical research, cell andmolecular biology, transgenic research and drug discovery. The number ofPubMed records containing the phrase “green fluorescent protein” exceeds5500 only within the last three years. Demand for labeling and detectionbased on the fluorescent protein technology is large and steady.

Currently, there are very few known natural pigments essentially encodedby a single gene, wherein both the substrate for pigment biosynthesisand the necessary catalytic moieties are provided within a singlepolypeptide chain. The limited availability of fluorescent markerproteins makes the current technology based on fluorescent proteins veryexpensive, rendering it unaffordable and inaccessible to many mid-size(or smaller) companies that are interested in using the technology.Therefore, there is a need for less expensive, readily availablefluorescent and/or colored materials.

BRIEF SUMMARY OF THE INVENTION

The subject invention provides new fluorescent and/or colored proteins,and polynucleotide sequences that encode these proteins. The subjectinvention further provides materials and methods useful for expressingthese detectable proteins in biological systems.

In specific embodiments, the subject invention provides advantageousfluorescent proteins. The invention also includes proteins substantiallysimilar to, or mutants or variants of, the exemplified proteins.

Another aspect of the subject invention pertains to polynucleotidesequences that encode the detectable proteins of the present invention.In one embodiment, the present invention provides polynucleotideconstructs comprising cDNA encoding novel colored and/or fluorescentproteins and mutants thereof.

In one embodiment, the invention provides nucleotide sequences of theinserts in pGEM-T vector (Promega), the conceptual translations of theseinserts, and special properties of purified protein products.

The proteins and polynucleotides of the present invention can be used asdescribed herein as colored and/or fluorescent (detectable) labels in avariety of ways, including but not limited to, as reporter genes formonitoring gene expression in living organisms, as protein tags fortracing the location of proteins within living cells and organisms, asreporter molecules for engineering various protein-based biosensors, andas genetically encoded pigments for modifying color and/or fluorescenceof living organisms or their parts.

In a specific embodiment, the proteins of the subject invention can beused in molecular fluorescent tagging whereby the coding region of aprotein of interest is fused with the coding region for a fluorescentprotein of the subject invention. The product of such a gene shows thefunctional characteristics of the protein of interest, but bears thefluorescent label allowing tracing its movements.

Advantageously, the present invention provides proteins andpolynucleotides to improve on the current technology of labeling anddetection by offering a wider choice of colors and biochemical featuresnever before provided by GFP and its modified variants.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the design of bacterial expression constructs for theproteins of interests of the present invention.

FIG. 2 shows the excitation and emission spectrum of Montiporamillepora, gbr1.

FIG. 3 shows the excitation and emission spectrum of Echinophylliaechinata, gbr3.

FIG. 4 shows the excitation and emission spectra of Mycediumelephantotus, gbr4.

FIG. 5 shows the excitation and emission spectra of Mycediumelephantotus, gbr5.

FIG. 6 shows the excitation and emission spectra of Echinophylliaechinata, gbr6.

FIG. 7 shows the excitation and emission spectra of Echinophylliaechinata, gbr7.

FIG. 8 shows the excitation and emission spectra of Echinophylliaechinata, gbr8.

FIG. 9 shows the excitation and emission spectra of Fungia scutaria,gbr9.

FIG. 10 shows the excitation and emission spectra of Galaxeafascicularis, gbr10.

FIG. 11 shows the excitation and emission spectra of Montiporaefflorescens, gbr14.

FIG. 12 shows the excitation and emission spectra of Porites pornes,gbr15.

FIG. 13 shows the excitation and emission spectra of Parites porites,gbr17.

FIG. 14 shows the excitation and emission spectra of Stylocoeniella sp.,gbr18.

FIG. 15 shows the excitation and emission spectra of Montiporaefflorescens, gbr24.

FIG. 16 shows the excitation and emission spectra of Fungia cf danai,gbr19.

FIG. 17 shows the excitation and emission spectra of Fungia cf danai,gbr20.

FIG. 18 shows the excitation and emission spectra of Galaxeafascicularis, gbr11.

FIG. 19 shows the excitation and emission spectra of Gonioporadjiboutiensis, gbr21.

FIG. 20 shows the excitation and emission spectra of Montiporaefflorescens, gbr22.

FIG. 21 shows the excitation and emission spectra of Stylocoeriella sp.,gbr23.

BRIEF DESCRIPTION OF THE SEQUENCES

SEQ ID NO:1 is the 5′ heel of an upstream primer used according to thesubject invention.

SEQ ID NO:2 is the 5′ heel of a downstream primer used according to thesubject invention.

SEQ ID NO:3 is the open reading frame of the cDNA encoding the gbr1protein of interest from Montipora millepora. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in mist feature.

SEQ ID NO:4 is the open reading frame of the cDNA encoding the gbr3protein of interest from Echinophyllia echinata. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:5 is the open reading frame of the cDNA encoding the gbr4protein of interest from Mycedium elephantotus. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:6 is the open reading frame of the cDNA encoding the gbr5protein of interest from Mycedium elephantotus. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:7 is the open reading frame of the cDNA encoding the gbr6protein of interest from Echinophyllia echinata. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature. Asequence identified in another misc_feature is derived from the cloningvector pGEM-T; it is included since in this particular construct itbecomes translated during protein expression.

SEQ ID NO:8 is the open reading frame of the cDNA encoding the gbr7protein of interest from Echinophyllia echinata. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:9 is the open reading frame of the cDNA encoding the gbr8protein of interest from Echinophyllia echinata. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:10 is the open reading frame of the cDNA encoding the gbr9protein of interest from Fungia scutaria. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:11 is the open reading frame of the cDNA encoding the gbr10protein of interest from Galaxea fascicularis. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:12 is the open reading frame of the cDNA encoding the gbr11protein of interest from Galaxea fascicularis. Parts of they sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:13 is the open reading frame of the cDNA encoding the gbr14protein of interest from Montipora efflorescens. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:14 is the open reading frame of the cDNA encoding the gbr15protein of interest from Porites porites. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:15 is the open reading frame of the cDNA encoding the gbr17protein of interest from Porites porites. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:16 is the open reading frame of the cDNA encoding the gbr18protein of interest from Stylocoeniella sp. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:17 is the open reading frame of the cDNA encoding the gbr19protein of interest from Fungia cf lanai. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:18 is the open reading frame of the cDNA encoding the gbr20protein of interest from Fungia cf danai. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:19 is the open reading frame of the cDNA encoding the gbr21protein of interest from Goniopora djiboutiensis. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:20 is the open reading frame of the cDNA encoding the gbr22protein of interest from Montipora efflorescens. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:21 is the open reading frame of the cDNA encoding the gbr23protein of interest from Stylocoeniella sp. Parts of the sequence thathave been artificially added during the cloning process to facilitategene expression in E. coli are identified in misc_feature.

SEQ ID NO:22 is the open reading frame of the cDNA encoding the gbr24protein of interest from Montipora efflorescens. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:23 is the open reading frame of the cDNA encoding the gbr25protein of interest from Montipora efflorescens. Parts of the sequencethat have been artificially added during the cloning process tofacilitate gene expression in E. coli are identified in misc_feature.

SEQ ID NO:24 is the amino acid sequence encoded by SEQ ID NO:3.

SEQ ID NO:25 is the amino acid sequence encoded by SEQ ID NO:4.

SEQ ID NO:26 is the amino acid sequence encoded by SEQ ID NO:5.

SEQ ID NO:27 is the amino acid sequence encoded by SEQ ID NO:6.

SEQ ID NO:28 is the amino acid sequence encoded by SEQ ID NO:7.

SEQ ID NO:29 is the amino acid sequence encoded by SEQ ID NO:8.

SEQ ID NO:30 is the amino acid sequence encoded by SEQ ID NO:9.

SEQ ID NO:31 is the amino acid sequence encoded by SEQ ID NO:10.

SEQ ID NO:32 is the amino acid sequence encoded by SEQ ID NO:11.

SEQ ID NO:33 is the amino acid sequence encoded by SEQ ID NO:12.

SEQ ID NO:34 is the amino acid sequence encoded by SEQ ID NO:13.

SEQ ID NO:35 is the amino acid sequence encoded by SEQ ID NO:14.

SEQ ID NO:36 is the amino acid sequence encoded by SEQ ID NO:15.

SEQ ID NO:37 is the amino acid sequence encoded by SEQ ID NO:16.

SEQ ID NO:38 is the amino acid sequence encoded by SEQ ID NO:17.

SEQ ID NO:39 is the amino acid sequence encoded by SEQ ID NO:18.

SEQ ID NO:40 is the amino acid sequence encoded by SEQ ID NO:19.

SEQ ID NO:41 is the amino acid sequence encoded by SEQ ID NO:20.

SEQ ID NO:42 is the amino acid sequence encoded by SEQ ID NO:21.

SEQ ID NO:43 is the amino acid sequence encoded by SEQ ID NO:22.

SEQ ID NO:44 is the amino acid sequence encoded by SEQ ID NO:23.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel fluorescent and colored proteinsisolated from marine organisms. In a particularly preferred embodiment,these proteins are fluorescent proteins. Specifically, exemplifiedherein are novel fluorescent proteins.

The subject invention further provides polynucleotide sequences encodingthese proteins. These polynucleotide sequences include open readingframes encoding the specific exemplified detectable proteins, as well asexpression constructs for expressing these proteins, for example, inbacterial hosts.

The proteins of the present invention can be readily, expressed by anyone of the recombinant technology methods known to those skilled in theart having the benefit of the instant disclosure. The preferred methodwill vary depending upon many factors and considerations, including thehost, and the cost and availability of materials and other economicconsiderations. The optimum production procedure for a given situationwill be apparent to those skilled in the art having the benefit of thecurrent disclosure.

The subject invention also concerns cells transformed with apolynucleotide of the present invention comprising a nucleotidesequences encoding a novel detectable protein. These cells may beprokaryotic or eukaryotic, plant or animal. In one embodiment, animals,such as fish, are transformed to provide them with a unique color orability to fluoresce. Polynucleotides providing the markers of thepresent invention are stable in a diverse range of hosts, includingprokaryotic and eukaryotic organisms, and the translation products arefully functional and capable of providing assayable characteristics.

In another embodiment, the present invention provides methods tosynthesize colored and fluorescent proteins in a recombinant cell.

In a specific embodiment, the proteins of the subject invention can beused in molecular fluorescent tagging whereby the coding region of aprotein of interest is fused with the coding region for a fluorescentprotein of the subject invention. The product of such a gene shows thefunctional characteristics of the protein of interest, but bears thefluorescent label allowing tracing its movements. See, for example,Eichinger, L., S. S. Lee and M. Schleicher (1999) “Dictyostelium asmodel system for studies of the actin cytoskeleton by moleculargenetics” Microsc Res Tech 47:124-134; Falk, M. M. and U. Lauf (2001)“High resolution, fluorescence deconvolution microscopy and tagging withthe autofluorescent tracers CFP, GFP, and YFP to study the structuralcomposition of gap junctions in living cells” Microsc Res Tech52:251-262; Kallal, L. and J. L. Benovic (2000) “Using green fluorescentproteins to study G-protein-coupled receptor localization andtrafficking” Trends Pharmacol Sci 21:175-180; and Laird, D. W., K.Jordan, T. Thomas, H. Qin, P. Fistouris and Q. Shao (2001) “Comparativeanalysis and application of fluorescent protein-tagged connexins”Microsc Res Tech 52:263-272.

In a further embodiment, the subject invention concerns polynucleotidescomprising an in-frame fusion of nucleotide sequences encoding multiplegenetic markers. In one embodiment, the polynucleotides encode thegenetic markers GUS, and a detectable protein of the subject invention.

The subject invention helps to provide a more abundant and diversecollection of proteins, which can be used in place of a GFP protein,such that new proteins are readily available for commercial exploitationby small companies that cannot take advantage of the current technologyfor financial reasons.

DEFINITIONS

As used herein, the terms “nucleic acid” and “polynucleotide” refer to adeoxyribonucleotide, ribonucleotide, or a mixed deoxyribonucleotide andribonucleotide polymer in either single- or double-stranded form, andunless otherwise limited, would encompass known analogs of naturalnucleotides that can function in a similar manner as naturally-occurringnucleotides.

As used herein, “a vector” is a DNA sequence having the elementsnecessary for the transcription/translation of a gene. Such elementswould include, for example, promoters. Various classes of promoters arewell known in the art and can be obtained commercially or assembled fromthe sequences and methods, which are also well known in the art. Anumber of vectors are available for expression and/or cloning, andinclude, but are not limited to, pBR322, pUC series, M13 series, andpBLUESCRIPT vectors (Stratagene, La Jolla, Calif.).

As used herein, the term “expression construct” refers to a combinationof nucleic acid sequences that provides for transcription of an operablylinked nucleic acid sequence. As used herein, the term “operably linked”refers to a juxtaposition of the components described wherein thecomponents are in a relationship that permits them to function in theirintended manner. In general, operably linked components are incontiguous relation.

Detectable Proteins

The subject invention provides novel fluorescent and/or coloredproteins. The novel colored and fluorescent proteins of the presentinvention can be detected using standard long-wave UV light sources or,preferably, optical designs appropriate for detecting agents with theexcitation/emission characteristics of the proteins exemplified herein(see, for example, FIGS. 2-21). These proteins are referred to herein as“detectable proteins” or “marker proteins.” The interaction of two ormore residues of the protein and external agents such as molecularoxygen give rise to the colored and/or fluorescent feature of theproteins.

Advantageously, the use of these proteins facilitate real-time detectionin vivo, a substrate is not required, and the relatively small size makethe proteins very advantageous.

Substitution of amino acids other than those specifically exemplified ornaturally present in the genetic marker proteins of the invention arealso contemplated within the scope of the present invention. Suchsubstitutions will create “variant proteins” within the scope of thesubject invention. Variants and fragments preferably have emission andexcitation maxima within 10 nm of the values shown in FIGS. 2-21. Forexample, non-natural amino acids can be substituted for the amino acidsof the marker proteins, so long as a marker protein having thesubstituted amino acids retains its ability to be detected throughfluorescence and/or color. Examples of non-natural amino acids include,but are not limited to, ornithine, citrulline, hydroxyproline,homoserine, phenylglycine, taurine, iodotyrosine, 2,4-diaminobutyricacid, α-amino isobutyric acid, 4-aminobutyric acid, 2-amino butyricacid, γ-amino butyric acid, ε-amino hexanoic acid, τ-amino hexanoicacid, 2-amino isobutyric acid, 3-amino propionic acid, norleucine,norvaline, sarcosine, homocitrulline, cysteic acid, τ-butylglycine,τ-butylalanine, phenylglycine, cyclohexylalanine, β-alanine,fluoro-amino acids, designer amino acids such as β-methyl amino acids,C-methyl amino acids, N-methyl amino acids, and amino acid analogues ingeneral. Non-natural amino acids also include amino acids havingderivatized side groups. Furthermore, any of the amino acids in theprotein can be of the D (dextrorotary) form or L (levorotary) form.Allelic variants of a protein sequence of a detectable protein used inthe present invention are also encompassed within the scope of theinvention.

Amino acids can be generally categorized in the following classes:non-polar, uncharged polar, basic, and acidic. Conservativesubstitutions whereby a marker protein having an amino acid of one classis replaced with another amino acid of the same class fall within thescope of the subject invention so long as a marker protein having thesubstitution still is detectable Table 1 below provides a listing ofexamples of amino acids belonging to each class.

TABLE 1 Class of Amino Acid Examples of Amino Acids Nonpolar Ala, Val,Leu, Ile, Pro, Met, Phe, Trp Uncharged Polar Gly, Ser, Thr, Cys, Tyr,Asn, Gln Acidic Asp, Glu Basic Lys, Arg, His

Polynucleotides

cDNA sequences encoding the proteins of the present invention areprovided. Polynucleotides of the present invention can be composed ofeither RNA or DNA. Preferably, the polynucleotides are composed of DNA.The subject invention also encompasses those polynucleotides that arecomplementary in sequence to the polynucleotides disclosed herein.

Specifically exemplified are DNA sequences that encode novel fluorescentproteins. These DNA sequences are set forth in SEQ. ID NOS. 3-23.

Sequences of the subject invention may utilize codons preferred forexpression by the selected host strains. These sequences may also havesites for cleavage by restriction enzymes, and/or initial, terminal, orintermediate DNA sequences which facilitate construction of readilyexpressed vectors.

Because of the degeneracy of the genetic code, a variety of differentpolynucleotide sequences can encode the detectable proteins of thepresent invention. In addition, it is well within the skill of a persontrained in the art to create alternative polynucleotide sequencesencoding the same, or essentially the same, detectable proteins of thesubject invention. These variant or alternative polynucleotide sequencesare within the scope of the subject invention. As used herein,references to “essentially the same” sequence refers to sequences whichencode amino acid substitutions, deletions, additions, or insertionswhich do not eliminate the detectability of the polypeptide encoded bythe polynucleotides of the present invention. Allelic variants of thenucleotide sequences encoding a genetic marker protein of the inventionare also encompassed within the scope of the invention.

The subject invention also concerns variants of the polynucleotides ofthe present invention that encode detectable proteins. Variant sequencesinclude those sequences wherein one or more nucleotides of the sequencehave been substituted, deleted, and/or inserted. The nucleotides thatcan be substituted for natural nucleotides of DNA have a base moietythat can include, but is not limited to, inosine, 5-fluorouracil,5-bromouracil, hypoxanthine, 1-methylguanine, 5-methylcytosine, andtritylated bases. The sugar moiety of the nucleotide in a sequence canalso be modified and includes, but is not limited to, arabinose,xylulose, and hexose. In addition, the adenine, cytosine, guanine,thymine, and uracil bases of the nucleotides can be modified withacetyl, methyl, and/or thio groups. Sequences containing nucleotidesubstitutions, deletions, and/or insertions can be prepared and testedusing standard techniques known in the art.

Polynucleotides and polypeptides of the subject invention can also bedefined in terms of more particular identity and/or similarity rangeswith those exemplified herein. The sequence identity will typically begreater than 60%, preferably greater than 75%, more preferably greaterthan 80%, even more preferably greater than 90%, and can be greater than95%. The identity and/or similarity of a sequence can be 49, 50, 51, 52,53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99% as compared to a sequenceexemplified herein. Unless otherwise specified, as used herein percentsequence identity and/or similarity of two sequences can be determinedusing the algorithm of Karlin and Altschul (1990), modified as in Karlinand Altschul (1993). Such an algorithm is incorporated into the NBLASTand XBLAST programs of Altschul et al. (1990). BLAST searches can beperformed with the NBLAST program, score=100, wordlength=12, to obtainsequences with the desired percent sequence identity. To obtain gappedalignments for comparison purposes, Gapped BLAST can be used asdescribed in Altschul et al. (1997). When utilizing BLAST and GappedBLAST programs, the default parameters of the respective programs(NBLAST and XBLAST) can be used.

The subject invention also contemplates those polynucleotide moleculeshaving sequences that are sufficiently homologous with thepolynucleotide sequences exemplified herein so as to permithybridization with that sequence under standard stringent conditions andstandard methods (Maniatis et al. 1982). As used herein, “stringent”conditions for hybridization refers to conditions wherein hybridizationis typically carried out overnight at 20-25 C below the meltingtemperature (Tm) of the DNA hybrid in 6×SSPE, 5×Denhardt's solution,0.1% SDS, 0.1 mg/ml denatured DNA. The melting temperature, Tm, isdescribed by the following formula (Beltz et al., 1983):

Tm=81.5 C+16.6 Log [Na+]+0.41(% G+C)−0.61(% formamide)−600/length ofduplex in base pairs.

Washes are typically carried out as follows:

(1) Twice at room temperature for 15 minutes in 1×SSPE, 0.1% SDS (lowstringency ash).

(2) Once at Tm−20 C for 15 minutes in 0.2×SSPE, 0.1% SDS (moderatestringency wash).

The polynucleotide sequences include the DNA strand sequence that istranscribed into RNA and the strand sequence that is complementary tothe DNA strand that is transcribed. The polynucleotide sequences alsoinclude both full-length sequences as well as shorter sequences derivedfrom the full-length sequences. The polynucleotide sequence includesboth the sense and antisense strands either as individual strands or inthe duplex.

Recombinant Hosts

Polynucleotide molecules containing DNA sequences encoding the coloredand/or fluorescent proteins of the present invention can be introducedinto a variety of host cells including bacterial cells, yeast cells,fungal cells, plant cells and animal cells. Methods by which theexogenous genetic material can be introduced into such host cells arewell known in the art.

In one embodiment, the invention provides a bacteria cell capable ofexpressing the novel colored and fluorescent proteins.

Plants, plant tissues, and plant cells bred to contain, or transformedwith, a polynucleotide of the invention are also contemplated by thepresent invention. In one embodiment, the polynucleotide encodes adetectable polypeptide shown in SEQ ID NOS. 7-10, or a functionalfragment or variant thereof. Plants within the scope of the presentinvention include monocotyledonous plants, such as rice, wheat, barley,oats, sorghum, maize, sugarcane, pineapple, onion, bananas, coconut,lilies, grasses, and millet; and dicotyledonous plants, such as peas,alfalfa, tomato, melon, chickpea, chicory, clover, kale, lentil,soybean, tobacco, potato, sweet potato, radish, cabbage, rape, appletrees, grape, cotton, sunflower, and lettuce; and conifers. Techniquesfor transforming plant cells with a gene are known in the art andinclude, for example, Agrobacterium infection, biolistic methods,electroporation, calcium chloride treatment, etc. Transformed cells canbe selected, redifferentiated, and grown into plants using standardmethods known in the art. The progeny of any transformed plant cells orplants are also included within the scope of the present invention.

The subject invention also concerns non-human transgenic animals whichhave incorporated into the host cell genome a polynucleotide of theinvention. Methods for producing transgenic animals, including mice,rats, pigs, sheep, cows, fish, and the like are well known in the art.

The subject invention also concerns methods for isolating transformantsexpressing a transgene. In one embodiment, an expression construct ofthe present invention comprising a transgene of interest operably linkedto a nucleotide sequence encoding a detectable marker of the presentinvention is used to transform a cell. Methods for transforming cellsare well known in the art. Transformed cells expressing the transgeneare selected by identifying those cells expressing a genetic marker ofthe invention.

Expression Constructs

An expression construct of the invention typically comprises astructural gene sequence (encoding a protein), an antisense sequence, orother polynucleotide sequences, or a site for insertion of suchsequences, operably linked to a polynucleotide of the present inventionencoding a marker. The structural gene can be a gene encoding a proteinfrom a prokaryotic or eukaryotic organism, for example, a human, mammal,insect, plant, bacteria, or virus. Proteins that can be encoded by agene sequence include, but are not limited to, enzymes, hormones,cytokines, interleukins, receptors, growth factors, immunoglobulins,transcription factors, and Bacillus thuringiensis (B.t.) crystal toxinproteins. Sequences encoding B.t. proteins which have codon usage forpreferential expression in plants are described in U.S. Pat. Nos.5,380,831; 5,567,862; 5,567,600; 6,013,523; and 6,015,891. An antisensesequence is a sequence wherein the RNA transcribed from the antisensesequence is at least partially complementary to RNA transcribed from agene encoding a protein.

Expression constructs of the invention will also generally includeregulatory elements that are functional in the intended host cell inwhich the expression construct is to be expressed. Thus, a person ofordinary skill in the art can select regulatory elements for use in forexample, bacterial host cells, yeast host cells, plant host cells,insect host cells, mammalian host cells, and human host cells.Regulatory elements include promoters, transcription terminationsequences, translation termination sequences, enhancers, andpolyadenylation elements.

An expression construct of the invention can comprise a promotersequence operably linked to a polynucleotide sequence encoding a markerof the invention. Promoters can be incorporated into a polynucleotideusing standard techniques known in the art. Multiple copies of promotersor multiple promoters can be used in an expression construct of theinvention. In a preferred embodiment, a promoter can be positioned aboutthe same distance from the transcription start site as it is from thetranscription start site in its natural genetic environment. Somevariation in this distance is permitted without substantial decrease inpromoter activity. A transcription start site is typically included inthe expression construct.

For expression in prokaryotic systems, an expression construct of theinvention can comprise promoters such as for example, alkalinephosphatase promoter, tryptophan (trp) promoter, lambda P_(L) promoter,β-lactamase promoter, lactose promoter, phoA promoter, T3 promoter, T7promoter, or tac promoter (de Boer et, al., 1983).

If the expression construct is to be provided in a plant cell, plantviral promoters, such as, for example, the cauliflower mosaic virus(CaMV) 35S (including the enhanced CaMV 35S promoter (see, for exampleU.S. Pat. No. 5,106,739)) or 19S promoter can be used. Plant promoterssuch as prolifera promoter, Ap3 promoter, heat shock promoters. T-DNA1′- or 2′-promoter of A. tumafaciens, polygalacturonase promoter,chalcone synthase A (CHS-A) promoter from petunia, tobacco PR-1apromoter, ubiquitin promoter, actin promoter, alcA gene promoter, pin2promoter (Xu et al., 1993), maize WipI promoter, maize trpA genepromoter (U.S. Pat. No. 5,625,136), maize CDPK gene promoter, andRUBISCO SSU promoter (U.S. Pat. No. 5,034,322) can also be used.Seed-specific promoters such as the promoter from a β-phaseolin gene (ofkidney bean) or a glycinin gene (of soybean), and others, can also beused Constitutive promoters (such as the CaMV, ubiquitin, actin, or NOSpromoter), tissue-specific promoters (such as the E8 promoter fromtomato), developmentally-regulated promoters, and inducible promoters(such as those promoters than can be induced by heat, light, hormones,or chemicals) are contemplated for use with the polynucleotides of theinvention.

For expression in animal cells, an expression construct of the inventioncan comprise suitable promoters that can drive transcription of thepolynucleotide sequence. If the cells are mammalian cells, thenpromoters such as, for example, actin promoter, metallothioneinpromoter, NF-kappaB promoter, EGR promoter, SRE promoter, IL-2 promoter,NFAT promoter, osteocalcin promoter, SV40 early promoter and SV40 latepromoter, Lck promoter, BMP5 promoter, TRP-1 promoter, murine mammarytumor virus long terminal repeat promoter. STAT promoter, or animmunoglobulin promoter can be used in the expression construct. Thebaculovirus polyhedrin promoter can be used with an expression constructof the invention for expression in insect cells. Promoters suitable foruse with an expression construct of the invention in yeast cellsinclude, but are not limited to, 3-phosphoglycerate kinase promoter,glyceraldehyde-3-phosphate dehydrogenase promoter, metallothioneinpromoter, alcohol dehydrogenase-2 promoter, and hexokinase promoter.

Expression constructs of the invention may optionally contain atranscription termination sequence, a translation termination sequence,signal peptide sequence, and/or enhancer elements. Transcriptiontermination regions can typically be obtained from the 3′ untranslatedregion of a eukaryotic or viral gene sequence. Transcription terminationsequences can be positioned downstream of a coding sequence to providefor efficient termination. Signal peptides are a group of short aminoterminal sequences that encode information responsible for therelocation of an operably linked mature polypeptide to a wide range ofpost-translational cellular destinations, ranging from a specificorganelle compartment to sites of protein action and the extracellularenvironment. Targeting marker gene products to an intended cellularand/or extracellular destination through the use of operably linkedsignal peptide sequence is contemplated for use with the polypeptides ofthe invention. Enhancers are cis-acting elements that increase activityof a promoter and can also be included in the expression construct.Enhancer elements are known in the art, and include, but are not limitedto, the CaMV 35S enhancer element, maize shrunken-1 enhancer element,cytomegalovirus (CMV) early promoter enhancer element, and the SV40enhancer element.

DNA sequences which direct polyadenylation of the mRNA encoded by thestructural gene can also be included in the expression construct. Theexpression constructs of the invention can also include a polynucleotidesequence that directs transposition of other genes, i.e., a transposon.

Applications

There are many ways in which the novel proteins of the subject inventioncan be used. In one embodiment, the proteins can be used to identifycells. In these methods the proteins can be used to express fluorescencein a cell. One use for this method is in pre-labeling isolated cells ora population of similar cells prior to exposing the cells to anenvironment in which different cell types are present. Detection offluorescence in only the original cells allows the location of suchcells to be determined and compared with the total population.

A second group of methods concerns the identification of cells that havebeen transformed with exogenous DNA of interest. Identifying cellstransformed with exogenous DNA is required in many in vitro proceduresas well as in in vivo applications such as gene therapy.

In one embodiment of the subject invention, a polynucleotide sequenceencoding a protein of the subject invention is fused to a DNA sequenceencoding a selected protein in order to directly label the encodedprotein. Expressing such a fluorescent and/or colored protein in a cellresults in the production of labeled proteins that can be readilydetected. This is useful in confirming that a protein is being producedby a chosen host cell. It also allows the location of the selectedprotein to be determined.

Cells that have been transformed with exogenous DNA can also beidentified without creating a fusion protein. Here, the method relies onthe identification of cells that have received a plasmid or vector thatcomprises at least two transcriptional or translational units. A firstunit encodes and directs expression of the desired protein, while thesecond unit encodes and directs expression of the detectable protein.Co-expression of the detectable protein from the second transcriptionalor translational unit ensures that cells containing the vector aredetected and differentiated from cells that do not contain the vector.

In methods to produce fluorescent molecular weight markers, a genesequence is generally fused to one or more DNA sequences that encodeproteins having defined amino acid sequences and the fusion proteins areexpressed from an expression vector. Expression results in theproduction of fluorescent proteins of defined molecular weight orweights that may be used as markers (following calculation of the sizeof the complete amino acid sequence).

Amino acid replacements that produce different color forms permitsimultaneous use of multiple reporter genes. Different colored proteinscan be used to identify multiple cell populations in a mixed cellculture or to track multiple cell types, enabling differences in cellmovement or migration to be visualized in real time without the need toadd additional agents or fix or kill the cells.

Other options include tracking and determining the ultimate location ofmultiple proteins within a single cell, tissue or organism; differentialpromoter analysis in which gene expression from two different promotersis determined in the same cell, tissue or organism; and FACS sorting ofmixed cell populations.

The techniques that can be used with spectrally separable proteins areexemplified by confocal microscopy, flow cytometry, and fluorescenceactivated cell sorting (FACS) using modular flow, dual excitationtechniques.

In one embodiment, the subject invention concerns polynucleotidescomprising an in-frame fusion of nucleotide sequences encoding multiplegenetic markers. For example, a polynucleotide of the invention maycomprise a first nucleotide sequence that is operably linked in-frame toa second nucleotide sequence. The polynucleotide encodes the amino acidsequences of the detectable protein and another genetic marker such thatthe genetic markers are in direct contact with one another, i.e., wherethe last amino acid of the fluorescent genetic marker is immediatelycontiguous with the first amino acid of the other genetic marker, orthey can be separated by a peptide linker sequence, for example, asdescribed in U.S. Pat. Nos. 5,891,680 and Li et al., 2001, that do notsubstantially alter functional activity of the genetic markers.

The subject invention also concerns kits comprising in one or morecontainers and a polynucleotide and/or protein of the present invention.

Additional useful applications of the technology described hereininclude, but are not limited to, the following:

FRET—Fluorescence Resonant Energy Transfer: This technique allowsobservation and quantification of molecular interactions. It requires atleast two fluorescent proteins of different colors. Currently the mostwidely used pair is CFP and YFP (mutated variants of GFP); the proteinsof the subject invention may be substituted for either or both of them.

REFERENCES

-   1. Hanson, M. R. and R. H. Kohler. 2001. GFP imaging: methodology    and application to investigate cellular compartmentation in plants.    J Exp Bot 52: 529-539.-   2. Pollok, B. A. and R. Heim. 1999. Using GFP in FRET-based    applications. Trends Cell Biol 9: 57-60.-   3. Schuttrigkeit, T. A., U. Zachariae, T. von Feilitzsch, J.    Wiehler, J. von Hummel, B. Steipe and M. E. Michel-Beyerle. 2001.    Picosecond time-resolved FRET in the fluorescent protein from    Discosoma Red (wt-DsRed). Chemphyschem 2: 325-328.-   4. Hillisch, A., M. Lorenz and S. Diekmann. 2001. Recent advances in    FRET: distance determination in protein-DNA complexes. Curr Opin    Struct Biol 11: 201-207.    FRAP—Fluorescence Redistribution After Photobleaching: This    technique quantifies the dynamics of tagged molecules or the    reporter molecules themselves. It involves in photobleaching    (burning out) of all the fluorescent molecules within a small area    by intense excitation light and monitoring the process of    fluorescence recovery within this area (due to migration of tagged    molecules from adjacent areas).

REFERENCES

-   1. Reits, E. A. and J. J. Neefjes. 2001. From fixed to FRAP:    measuring protein mobility and activity in living cells. Nat Cell    Biol 3: E145-147.-   2. Houtsmuller, A. B. and W. Vermeulen. 2001. Macromolecular    dynamics in living cell nuclei revealed by fluorescence    redistribution after photobleaching. Histochem Cell Biol 115: 13-21.    “Fluorescent timer” applications: one of the proteins exemplified    herein—scubRFP—due to its natural spectroscopic properties, can be    used as a reporter that changes color with time. Such reporters make    it possible to estimate the time elapsed since the reporter protein    was synthesized by quantifying its color. In addition, since the    maturation speed (the rate of conversion from green to red) in    scubRFP can be increased by UV-A light, it is possible to adjust its    timing scale: experiments that need timing in shorter intervals may    use appropriate background UV illumination to speed up the    green-to-red conversion.

REFERENCES

-   1. Terskikh, A. V., A. Fradkov, A. Zaraiskiy, A. V. Kajava, M.    Matz, S. Kim, I. Weissman and P. Siebert. 2000. “Fluorescent timer”:    Protein that changes color over time. Molecular Biology of the Cell    11: 648.-   2. Verkhusha, V. V., H. Otsuna, T. Awasaki, H. Oda, S. Tsukita    and K. Ito. 2001. An enhanced mutant of red fluorescent protein    DsRed for double labeling and developmental timer of neural fiber    bundle formation. Journal of Biological Chemistry 276: 29621-29624.    “Light-inducible fluorescence”: since the red fluorescence of    scubRFP can be induced by exposure to UV-A light, it is possible to    use this protein as a light-inducible reporter. Such a reporter can    be used for studying molecular dynamics, in a way that is analogous    to FRAP (see above). A small area can be irradiated by the    fluorescence-inducing light, after which the process of    redistribution of active fluorescent molecules from the irradiated    spot can be followed.

REFERENCES

-   1. Ando, R., H. Hama, M. Yamamoto-Hino, H. Mizuno and A.    Miyawaki. 2002. An optical marker based on the UV-induced    green-to-red photoconversion of a fluorescent protein. Proceedings    of the National Academy of Sciences of the United States of America    99: 12651-12656.-   2. Patterson, G. H. and J. Lippincott-Schwartz. 2002. A    photoactivatable GFP for selective photolabeling of proteins and    cells. Science 297: 1873-1877.-   3. Chudakov, D. M., V. V. Belousov, A. G. Zaraisky, V. V.    Novoselov, D. B. Staroverov, D. B. Zorov, S. Lukyanov and K. A.    Lukyanov. 2003. Kindling fluorescent proteins for precise in vivo    photolabeling (vol 21, pg 191, 2003). Nature Biotechnology 21:    452-452.    Coloring of biological objects for decorative and other    non-scientific purposes. Examples: producing decorative fish for    aquariums; coloring of fur, wool and milk by means of genetic    modifications of appropriate animals; and coloring of decorative    plants. Such uses can be implemented by a person skilled in the art    having the benefit of the teachings of the current disclosure.    All patents, patent applications, provisional applications, and    publications referred to or cited herein are incorporated by    reference in their entirety, including all figures and tables, to    the extent they are not inconsistent with the explicit teachings of    this specification.

Following are examples which illustrate procedures for practicing theinvention. These examples should not be construed as limiting. Allpercentages are by weight and all solvent mixture proportions are byvolume unless otherwise noted.

Example 1 Bacterial Expression Construct

As illustrated in FIG. 1, to prepare a bacterial expression construct,the ORF of the target detectable protein can be amplified by means ofpolymerase chain reaction (PCR), using primers corresponding to thebeginning and end of the protein's ORF. The upstream primer can carry a5′-heel ttgattgattgaaggagaaatatcATG (SEQ ID NO:1), which encodes threetermination codons in three frames (bold), followed by the ribosomebinding site (underlined), 6 spacer bases and initiation ATG codon.

The downstream primer can encode a 6×His tag in place of the originaltermination codon (the heel sequence can be 5′-tta tta gtg atg gtg atggtg atg (SEQ ID NO:2)), to facilitate protein purification by means ofmetal-affinity chromatography.

The products of amplification can be cloned into pGEM-T vector (Promega)using manufacturer-provided reagents and protocol. The expressing clonescan be identified after overnight growth of the colonies by theirfluorescent appearance.

Example 2 Excitation and Emission Spectra of the Detectable Proteins

The excitation spectra were measured from the proteins purified afterbacterial expression. The spectra are shown in FIGS. 2-21. Emissionspectra (dotted lines) were measured using USB2000 uv-vis spectrometer(Ocean Optics), excitation spectra (solid lines)—usingspectrofluorometer LS-50B (Perkin Elmer). The indicated positions ofexcitation and emission maxima are accurate within 5 nm.

Example 3 Multiple Marker Constructs

There are several advantages associated with the use of fusion markers,including: 1) achievement of combined functionalities in a singletranscription unit, 2) reduced usage of genetic elements, such aspromoters and terminators, for expressing multiple marker genes, 3)reduced overall length of insertion sequences that may lead to increasedtransformation efficiency, and most importantly 4) elimination ofmolecular interactions between adjacent genetic elements. Such unwantedinteractions are frequently encountered when multiple expression unitsassociated with different marker genes are used simultaneously and oftencomplicate the interpretation of expression results.

In an effort to improve marker functionality and versatility, severaltranslational fusions between two genetic markers have been developed.Datla et al. (1991; U.S. Pat. No. 5,639,663) created a bifunctionalfusion between GUS and neomycin phosphotransferase (NPTII) to provide abiochemically assayable reporter activity and a conditionally selectablegrowth advantage for use in plant transformation. Another bifunctionalfusion, between GUS and GFP, was also developed to provide bothindicative and assayable reporter activities for monitoring transientand stable transgene expression in plant cells (Quaedvlieg et al.,1998). More recently, Li et al. (2001) constructed a bifunctional fusionbetween GFP and NPTII and successfully used this marker for continuousanalysis of promoter activity and transgene expression in transgenicgrape plants throughout the entire process of plant development.

Small portions of a protein that provide unique functions such asprotein/DNA/substrate binding activity can be inserted into anotherheterologous protein to create a hybrid fusion with enhancedfunctionality and utility. In other cases, an entire gene or protein ofinterest has been fused in-frame to another heterologous gene or proteinto form a double fusion to provide combined functionalities. Productionof multiple proteins using fusion constructs composed of two genes fromtransgenic plants has been demonstrated previously (U.S. Pat. No.6,455,759).

In one embodiment, the subject invention provides cells transformed witha polynucleotide of the present invention comprising an in-frame fusionof nucleotide sequences encoding multiple markers. Preferably, thepolynucleotide sequence is provided in an expression construct of theinvention. The transformed cell can be a prokaryotic cell, for example,a bacterial cell such as E. coli or B. subtilis, or the transformed cellcan be a eukaryotic cell, for example, a plant or animal cell. Animalcells include human cells, mammalian cells, avian cells, fish cells andinsect cells. Mammalian cells include, but are not limited to, COS, 3T3,and CHO cells.

Genetic markers that can be used in conjunction with the detectableproteins of the present invention are known in the art and include, forexample, polynucleotides encoding proteins that confer a conditionallyselective growth advantage, such as antibiotic resistance andherbicide-resistance; polynucleotides encoding proteins that confer abiochemically assayable reporter activity; and polynucleotides encodingproteins that confer an indicative reporter activity. Examples ofpolynucleotides encoding proteins providing antibiotic resistanceinclude those that can provide for resistance to one or more of thefollowing antibiotics: hygromycin, kanamycin, bleomycin, G418,streptomycin, paromomycin, and spectinomycin. Kanamycin resistance canbe provided by neomycin phosphotransferase (NPTII). Examples ofpolynucicotides encoding proteins providing herbicide resistance includethose that can provide for resistance to phosphinothricinacetyltransferase or glyphosate. Examples of genetic markers that conferassayable or indicative reporters activity that can be used in thepresent invention include, but are not limited to, polynucleotidesencoding β-glucuronidase (GUS), β-galactosidase, chloramphenicolacetyltransferase (CAT), luciferase, nopaline synthase (NOS), and greenfluorescence protein (GFP).

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication.

1. A protein comprising an amino sequence selected from the groupconsisting of SEQ. ID NOs:24-44, fragments of these sequences, andvariants of these sequences and fragments; wherein the amino acidsequence of a variant is at least 90% identical to at least one of saidSEQ ID NOs:24-44 or a fragment of one of said sequences; and whereinsaid fragments and said variants have emission and excitation maximathere are within ±10 nm of the emission and excitation maxima for atleast one of SEQ ID NOs:24-44.
 2. The protein, according to claim 1,wherein said protein has an amino acid sequence selected from the groupconsisting of SEQ. ID NOs:24-44.
 3. A polynucleotide sequence thatencodes a protein comprising an amino sequence selected from the groupconsisting of SEQ. ID NOs:24-44, fragments of these sequences, andvariants of these sequences and fragments; wherein the amino acidsequence of a variant is at least 90% identical to at least one of saidSEQ ID NOs:24-44, or a fragment of one of said sequences; and whereinsaid fragments and said variants have emission and excitation maximathere are within ±10 nm of the emission and excitation maxima for atleast one of SEQ ID NOs:24-44.
 4. The polynucleotide sequence, accordingto claim 3, wherein said polynucleotide has a sequence is selected fromthe group consisting of SEQ. ID NOs:3-23.
 5. Use of a protein, whereinsaid protein comprises an amino sequence selected from the groupconsisting of SEQ. ID NOs:24-44, fragments of these sequences, andvariants of these sequences and fragments; wherein the amino acidsequence of a variant is at least 90% identical to at least one of saidSEQ ID NOs:24-44, or a fragment of one of said sequences; and whereinsaid fragments and said variants have emission and excitation maximathere are within ±10 nm of the emission and excitation maxima for atleast one of SEQ ID NOs:24-44, for monitoring gene expression; as a tagfor tracing the location of proteins; as a reporter molecule in aprotein-based biosensor; or as a pigment for modifying the color, orfluorescence, or both, of living tissue.
 6. The use, according to claim5, wherein a polynucleotide that encodes said protein is fused with apolynucleotide that encodes a protein of interest.